Proposals have been made in the past to provide an underground oil spill recovery system installed in a well casing using a submersible pump and a fluid level sensor. The level sensor is of such construction as to discern between oil and water. The submersible pump is turned on when the sensor registers a sufficient depth of oil below the pump. The pump and sensor are secured at fixed locations in the well. Their positions do not change as the oil and water levels in the well rise and fall. This system requires a 6 to 8 inch inside diameter well casing. Such an oil recovery system is disclosed in U.S. Pat. No. 4,273,650 to Solomon, issued June 16, 1981.
Another underground oil spill recovery system is currently being sold by Oil Recovery Systems of Greenville, N.H. The system uses a floating oil recovery unit comprised of a receptacle for the oil and a semipermeable membrane on the periphery of the receptacle. The membrane allows only liquid hydrocarbons to pass through it and prevents the passage of water. The membrane is submerged about 1/4 inch into the water so that all hydrocarbons on the water will contact the membrane. As the receptacle is filled by the hydrocarbons, which passed through the membrane, a float inside the receptacle rises and triggers a pump which empties the receptacle of the liquid hydrocarbons. This system depends upon the semipermeable membrane to separate the oil from the water. This system usually requires a 24-inch diameter well casing. Such an oil recovery system is disclosed in U.S. Pat. No. 4,243,529 to Strauss, issued June 15, 1979.
Another device for removing floating material from water uses a sonic transponder or the like to position the intake of the skimming system. This system was not designed to operate in a well casing and takes in water and oil during its operation. Such a device is disclosed in U.S. Pat. No. 4,154,678.
None of the oil recovery systems described above disclose apparatus which uses the principle of specific gravity to ensure that only oil enters the apparatus for recovery purposes. A device using such principle would simplify and lower the cost of an oil recovery process. Moreover, none of the oil recovery systems described above discloses apparatus which can be used in a 2-inch or 4-inch inside diameter well casing. Such an apparatus would be easier to operate and be less expensive to install than conventional systems. None of the systems described above can operate without an electrical control or sensing unit which governs the positioning of the system itself or the fluid removal thereby.
The proposed system of the prsent invention does not require electrical power to operate. Without electrical controls, the danger of fire and explosion is reduced and the cost of the equipment is lowered. None of the aforementioned systems uses piping to hold an oil recovery unit vertically in the well and centered in the well casing as does the present invention. The present invention further uses those piping supports as conduits for liquid hydrocarbons, water and air.
Because of the aforementioned deficiencies of conventional underground oil recovery systems, a need exists for improvements in the recovery of liquid hydrocarbons residing on ground water.